Question

A 25 kg mass or a 30 kg mass going 5 m/s.
Two 10 kg masses, one going 75 m/s, one going 45 m/s.
A car at rest or a car rolling down a hill.
A heavy bike or a light bike.
Circle the one with more Kinetic Energy

Answer 1

Circle these (more kinetic energy):

- The 30 kg mass going 5 m/s.
(KE = 1/2 m v^2: 30 kg → KE = 0.5·30·5^2 = 375 J vs 25 kg → 312.5 J)

- The 10 kg mass going 75 m/s.
(KE: 0.5·10·75^2 = 28,125 J vs 0.5·10·45^2 = 10,125 J)

- The car rolling down a hill (a car at rest has zero KE).

- The heavy bike (at the same speed the heavier object has more KE).